Conventionally, an integrated circuit package provides for electrical connections from an integrated circuit chip to external conductors and for protection of the chip from the external environment. Additionally, management of electromagnetic emission and thermal dissipation are increasingly important considerations in the development of improved packaging for integrated circuit chips.
Large integrated circuits, for example, application specific integrated circuits (ASICs) used in telecommunications and other applications, may dissipate powers in excess of several Watts. Consequently, it may be necessary to provide an integrated circuit package with a heat sink. Conventionally a heat sink for a packaged integrated circuit may be provided by mounting the chip in thermal contact with a slug of thermally conductive metal or alloy having an exposed surface for dissipation of heat. Where greater heat dissipation is required, a heat sink may be provided with fins extending laterally of the package, to increase the exposed surface area for heat dissipation. However, the latter structure, of course, adds considerably to the size of the package.
To prevent electromagnetic interference (EMI) from unwanted radiated emissions generated by integrated circuits in electronic equipment, electromagnetic shielding of electronic systems may be required to meet various regulatory standards. Addition of shielding to meet increasingly stringent international regulations and standards for controlling electromagnetic interference (EMI), e.g. FCC requirements, may add significant cost to a system.
Typically, materials having characteristics suitable for application as a heat sink, i.e. good thermal conductivity, do not also have the characteristics required for electromagnetic shielding. With the continued drive towards reducing the dimensions of integrated circuit packages, conventional packaging techniques are severely challenged in providing both effective heat dissipation or control of electromagnetic interference in a readily manufacturable and reliable package.
The present invention seeks to provide an integrated circuit package with improved thermal management and control of electromagnetic interference.